Abdul Hadi Arwani, a Syrian preacher at An-Noor Mosque in Acton, was found with a gunshot wound to his chest.YouTube

The family of murdered Syrian cleric Abdul Hadi Arwani have paid tribute to their "peaceful" father, and say he was "actively involved in the fight against extremism." Arwani, 48, was found dead with gunshot wounds in the seat of his Volkswagen Passat in Webley on Tuesday.

Counter-terror police are now investigating the murder of the former Imam of the An-Noor Mosque in Acton, who was a fierce critic of the Assad regime in Syria.

Abdelmoneim Mahmoud, one of Arwani's six children, posted a message on Facebook on behalf of his family, paying tribute to him as a critic of "terror and oppression."

"He just loved to help people. He did not care what your background, race or status was. My father was actively involved in the fight against extremism, campaigning for peace and advocating the importance of democracy and freedom," said Abdelmoneim.

"He loved the idea of freedom for all, regardless of religion, race and background. He spoke up and out against the crime of terror and oppression wherever he found it."

Reports in the wake of Arwani's murder suggested that he was forced to step down as mosque imam after terror suspect Mohammed Ahmed Mohamed evaded a supervision order at the mosque, and fled wearing a burqa.

The son of radical preacher Abu Hamza was recently invited to speak at the mosque.

Fellow activists said on 8 April that Arwani was a fierce opponent of Isis, the jihadist group that has seized control of swathes of Syria, and supported the secular Free Syrian Army.

A post-mortem examination into Mr Arwani's death will take place today (9 April).